Song was returned to the Red Sox on Friday, Rob Bradford of WEEI.com reports.
Song joined the Phillies in December as a Rule 5 Draft pick, but he missed the first half of the 2023 season due to a back injury and had allowed nine earned runs on 12 hits and 11 walks through 11 innings of relief between Low-A Clearwater, Double-A Reading and Triple-A Lehigh Valley. Philadelphia designated him for assignment last weekend and now he's back with the organization that originally drafted him out of the United States Naval Academy in 2019.